1. Field of the Invention
The present invention relates to a stator core of a torque motor, and more particularly to a stator core of a torque motor which can improve an assembling workability of the stator core without reducing a generation torque.
2. Description of Related Art
In conventional, for example, as a throttle control apparatus for controlling so as to open and close a throttle valve of an internal combustion engine, there has been known an apparatus in which a torque motor is used in a rotation driving portion.
The torque motor used in this kind of apparatus is a motor which utilizes a torque generated within a limited range of rotation angle or in a restricted state. Accordingly, the motor is generally provided with a pair of two-divided stator cores, a coil iron core assembled so as to connect end portions of a pair of stator cores, and a coil wound around the coil iron core, and is structured such that a rotor provided with a permanent magnet in an outer peripheral portion is rotatably arranged between circular arc pole tooth portions arranged so as to oppose to each other in a pair of stator cores.
Further, in conventional, as this kind of torque motor, there has been proposed in Japanese Unexamined Patent Publication No. 10-178769 a torque motor having a structure in which coil winding portions of a pair of stator cores are joined together by coil iron cores, in order to simplify the assembling workability of the stator core.
However, in this torque motor, since the coil iron cores are connected to a pair of stator cores by engagement connection portions, a gap tends to be generated in the connection portion due to vibration or the like. When the gap is generated, there is generated a problem that a magnetic circuit of the stator cores is changed and a torque property of the motor becomes unstable.
Thus, in order to aim an improvement of the stability in the torque property and the assembling workability in the stator core, there has been considered a stator core having a structure in which both ends of the circular arc pole tooth portions of a pair of stator cores are integrally connected to each other. However, in the case that both ends of both side stator cores are integrally connected, the magnetic circuit formed between the pole tooth portions of the stator cores and the rotor is short circuited in the pole tooth portions. Accordingly, there has been generated a problem that the generation torque of the motor is reduced.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided a stator core of a torque motor comprising:
arm portions for pressure inserting a coil portion; and
pole tooth portions arranged in a columnar space for inserting a rotor in an opposing manner,
wherein a stator core entire body having a front entire shape of the stator core and a pair of stator core divided bodies approximately divided into two pieces are connected in an overlapping manner, a pair of stator core divided bodies are arranged in both sided so as to be provided with a space portion therebetween and oppose the pole tooth portions to each other, and a portion in the vicinity of the space portion of the stator core entire body connects the stator core separation bodies in both sides as a connection portion and is integrally formed.
The object of the present invention is to provide a stator core of a torque motor which can improve an assembling workability at a time of manufacturing without generating reduction of the generation torque, on the basis of the structure mentioned above.
In accordance with the stator core of the torque motor on the basis of the present invention, the stator core entire body and the stator core divided bodies are connected in an overlapping manner, and the portion in the vicinity of the space portion of the stator core entire body connects the stator core separation bodies in both sides as the connection portion and is integrally formed. Therefore, when pressure inserting the coil portion into the arm portion, it is possible to assemble the coil portion within the arm portion by a simple work constituted only by pressure inserting the coil portion into the arm portion, in comparison with the conventional case that the coil iron core of the coil portion is fitted to the end portions of both side stator cores in the state in which a pair of two-divided stator cores are fixed to the predetermined positions.
Further, in the torque motor using the stator core, there is a possibility that the pole tooth portions of both side stator cores short circuit the magnetic circuit by the connection portion so as to reduce the generation torque, however, a thickness of the connection portion is restricted so that the reduction of the generation torque becomes minimum by adjusting a thickness of the stator core entire body or a number of lamination of the laminated metal sheets within a range having a bearing force at the pressure inserting time, whereby it is possible to stably generate a torque required as the torque motor. Further, in the torque motor using the stator core, since the coil iron core of the coil portion is pressure inserted, it is possible to reduce a risk that the gap is generated between the coil iron core and the stator core due to the vibration or the like, and it is possible to secure an improved torque property.